1 /* 2 * Loopback soundcard 3 * 4 * Original code: 5 * Copyright (c) by Jaroslav Kysela <perex@perex.cz> 6 * 7 * More accurate positioning and full-duplex support: 8 * Copyright (c) Ahmet İnan <ainan at mathematik.uni-freiburg.de> 9 * 10 * Major (almost complete) rewrite: 11 * Copyright (c) by Takashi Iwai <tiwai@suse.de> 12 * 13 * A next major update in 2010 (separate timers for playback and capture): 14 * Copyright (c) Jaroslav Kysela <perex@perex.cz> 15 * 16 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License as published by 18 * the Free Software Foundation; either version 2 of the License, or 19 * (at your option) any later version. 20 * 21 * This program is distributed in the hope that it will be useful, 22 * but WITHOUT ANY WARRANTY; without even the implied warranty of 23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 24 * GNU General Public License for more details. 25 * 26 * You should have received a copy of the GNU General Public License 27 * along with this program; if not, write to the Free Software 28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 29 * 30 */ 31 32 #include <linux/init.h> 33 #include <linux/jiffies.h> 34 #include <linux/slab.h> 35 #include <linux/time.h> 36 #include <linux/wait.h> 37 #include <linux/moduleparam.h> 38 #include <linux/platform_device.h> 39 #include <sound/core.h> 40 #include <sound/control.h> 41 #include <sound/pcm.h> 42 #include <sound/info.h> 43 #include <sound/initval.h> 44 45 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>"); 46 MODULE_DESCRIPTION("A loopback soundcard"); 47 MODULE_LICENSE("GPL"); 48 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}"); 49 50 #define MAX_PCM_SUBSTREAMS 8 51 52 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-MAX */ 53 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* ID for this card */ 54 static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0}; 55 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8}; 56 static int pcm_notify[SNDRV_CARDS]; 57 58 module_param_array(index, int, NULL, 0444); 59 MODULE_PARM_DESC(index, "Index value for loopback soundcard."); 60 module_param_array(id, charp, NULL, 0444); 61 MODULE_PARM_DESC(id, "ID string for loopback soundcard."); 62 module_param_array(enable, bool, NULL, 0444); 63 MODULE_PARM_DESC(enable, "Enable this loopback soundcard."); 64 module_param_array(pcm_substreams, int, NULL, 0444); 65 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver."); 66 module_param_array(pcm_notify, int, NULL, 0444); 67 MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes."); 68 69 #define NO_PITCH 100000 70 71 struct loopback_pcm; 72 73 struct loopback_cable { 74 spinlock_t lock; 75 struct loopback_pcm *streams[2]; 76 struct snd_pcm_hardware hw; 77 /* flags */ 78 unsigned int valid; 79 unsigned int running; 80 unsigned int pause; 81 }; 82 83 struct loopback_setup { 84 unsigned int notify: 1; 85 unsigned int rate_shift; 86 unsigned int format; 87 unsigned int rate; 88 unsigned int channels; 89 struct snd_ctl_elem_id active_id; 90 struct snd_ctl_elem_id format_id; 91 struct snd_ctl_elem_id rate_id; 92 struct snd_ctl_elem_id channels_id; 93 }; 94 95 struct loopback { 96 struct snd_card *card; 97 struct mutex cable_lock; 98 struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2]; 99 struct snd_pcm *pcm[2]; 100 struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2]; 101 }; 102 103 struct loopback_pcm { 104 struct loopback *loopback; 105 struct snd_pcm_substream *substream; 106 struct loopback_cable *cable; 107 unsigned int pcm_buffer_size; 108 unsigned int buf_pos; /* position in buffer */ 109 unsigned int silent_size; 110 /* PCM parameters */ 111 unsigned int pcm_period_size; 112 unsigned int pcm_bps; /* bytes per second */ 113 unsigned int pcm_salign; /* bytes per sample * channels */ 114 unsigned int pcm_rate_shift; /* rate shift value */ 115 /* flags */ 116 unsigned int period_update_pending :1; 117 /* timer stuff */ 118 unsigned int irq_pos; /* fractional IRQ position */ 119 unsigned int period_size_frac; 120 unsigned long last_jiffies; 121 struct timer_list timer; 122 }; 123 124 static struct platform_device *devices[SNDRV_CARDS]; 125 126 static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x) 127 { 128 if (dpcm->pcm_rate_shift == NO_PITCH) { 129 x /= HZ; 130 } else { 131 x = div_u64(NO_PITCH * (unsigned long long)x, 132 HZ * (unsigned long long)dpcm->pcm_rate_shift); 133 } 134 return x - (x % dpcm->pcm_salign); 135 } 136 137 static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x) 138 { 139 if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */ 140 return x * HZ; 141 } else { 142 x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ, 143 NO_PITCH); 144 } 145 return x; 146 } 147 148 static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm) 149 { 150 int device = dpcm->substream->pstr->pcm->device; 151 152 if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK) 153 device ^= 1; 154 return &dpcm->loopback->setup[dpcm->substream->number][device]; 155 } 156 157 static inline unsigned int get_notify(struct loopback_pcm *dpcm) 158 { 159 return get_setup(dpcm)->notify; 160 } 161 162 static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm) 163 { 164 return get_setup(dpcm)->rate_shift; 165 } 166 167 static void loopback_timer_start(struct loopback_pcm *dpcm) 168 { 169 unsigned long tick; 170 unsigned int rate_shift = get_rate_shift(dpcm); 171 172 if (rate_shift != dpcm->pcm_rate_shift) { 173 dpcm->pcm_rate_shift = rate_shift; 174 dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size); 175 } 176 if (dpcm->period_size_frac <= dpcm->irq_pos) { 177 dpcm->irq_pos %= dpcm->period_size_frac; 178 dpcm->period_update_pending = 1; 179 } 180 tick = dpcm->period_size_frac - dpcm->irq_pos; 181 tick = (tick + dpcm->pcm_bps - 1) / dpcm->pcm_bps; 182 dpcm->timer.expires = jiffies + tick; 183 add_timer(&dpcm->timer); 184 } 185 186 static inline void loopback_timer_stop(struct loopback_pcm *dpcm) 187 { 188 del_timer(&dpcm->timer); 189 dpcm->timer.expires = 0; 190 } 191 192 #define CABLE_VALID_PLAYBACK (1 << SNDRV_PCM_STREAM_PLAYBACK) 193 #define CABLE_VALID_CAPTURE (1 << SNDRV_PCM_STREAM_CAPTURE) 194 #define CABLE_VALID_BOTH (CABLE_VALID_PLAYBACK|CABLE_VALID_CAPTURE) 195 196 static int loopback_check_format(struct loopback_cable *cable, int stream) 197 { 198 struct snd_pcm_runtime *runtime, *cruntime; 199 struct loopback_setup *setup; 200 struct snd_card *card; 201 int check; 202 203 if (cable->valid != CABLE_VALID_BOTH) { 204 if (stream == SNDRV_PCM_STREAM_PLAYBACK) 205 goto __notify; 206 return 0; 207 } 208 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]-> 209 substream->runtime; 210 cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]-> 211 substream->runtime; 212 check = runtime->format != cruntime->format || 213 runtime->rate != cruntime->rate || 214 runtime->channels != cruntime->channels; 215 if (!check) 216 return 0; 217 if (stream == SNDRV_PCM_STREAM_CAPTURE) { 218 return -EIO; 219 } else { 220 snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]-> 221 substream, SNDRV_PCM_STATE_DRAINING); 222 __notify: 223 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]-> 224 substream->runtime; 225 setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]); 226 card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card; 227 if (setup->format != runtime->format) { 228 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, 229 &setup->format_id); 230 setup->format = runtime->format; 231 } 232 if (setup->rate != runtime->rate) { 233 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, 234 &setup->rate_id); 235 setup->rate = runtime->rate; 236 } 237 if (setup->channels != runtime->channels) { 238 snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE, 239 &setup->channels_id); 240 setup->channels = runtime->channels; 241 } 242 } 243 return 0; 244 } 245 246 static void loopback_active_notify(struct loopback_pcm *dpcm) 247 { 248 snd_ctl_notify(dpcm->loopback->card, 249 SNDRV_CTL_EVENT_MASK_VALUE, 250 &get_setup(dpcm)->active_id); 251 } 252 253 static int loopback_trigger(struct snd_pcm_substream *substream, int cmd) 254 { 255 struct snd_pcm_runtime *runtime = substream->runtime; 256 struct loopback_pcm *dpcm = runtime->private_data; 257 struct loopback_cable *cable = dpcm->cable; 258 int err, stream = 1 << substream->stream; 259 260 switch (cmd) { 261 case SNDRV_PCM_TRIGGER_START: 262 err = loopback_check_format(cable, substream->stream); 263 if (err < 0) 264 return err; 265 dpcm->last_jiffies = jiffies; 266 dpcm->pcm_rate_shift = 0; 267 spin_lock(&cable->lock); 268 cable->running |= stream; 269 cable->pause &= ~stream; 270 spin_unlock(&cable->lock); 271 loopback_timer_start(dpcm); 272 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) 273 loopback_active_notify(dpcm); 274 break; 275 case SNDRV_PCM_TRIGGER_STOP: 276 spin_lock(&cable->lock); 277 cable->running &= ~stream; 278 cable->pause &= ~stream; 279 spin_unlock(&cable->lock); 280 loopback_timer_stop(dpcm); 281 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) 282 loopback_active_notify(dpcm); 283 break; 284 case SNDRV_PCM_TRIGGER_PAUSE_PUSH: 285 spin_lock(&cable->lock); 286 cable->pause |= stream; 287 spin_unlock(&cable->lock); 288 loopback_timer_stop(dpcm); 289 break; 290 case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: 291 spin_lock(&cable->lock); 292 dpcm->last_jiffies = jiffies; 293 cable->pause &= ~stream; 294 spin_unlock(&cable->lock); 295 loopback_timer_start(dpcm); 296 break; 297 default: 298 return -EINVAL; 299 } 300 return 0; 301 } 302 303 static void params_change_substream(struct loopback_pcm *dpcm, 304 struct snd_pcm_runtime *runtime) 305 { 306 struct snd_pcm_runtime *dst_runtime; 307 308 if (dpcm == NULL || dpcm->substream == NULL) 309 return; 310 dst_runtime = dpcm->substream->runtime; 311 if (dst_runtime == NULL) 312 return; 313 dst_runtime->hw = dpcm->cable->hw; 314 } 315 316 static void params_change(struct snd_pcm_substream *substream) 317 { 318 struct snd_pcm_runtime *runtime = substream->runtime; 319 struct loopback_pcm *dpcm = runtime->private_data; 320 struct loopback_cable *cable = dpcm->cable; 321 322 cable->hw.formats = (1ULL << runtime->format); 323 cable->hw.rate_min = runtime->rate; 324 cable->hw.rate_max = runtime->rate; 325 cable->hw.channels_min = runtime->channels; 326 cable->hw.channels_max = runtime->channels; 327 params_change_substream(cable->streams[SNDRV_PCM_STREAM_PLAYBACK], 328 runtime); 329 params_change_substream(cable->streams[SNDRV_PCM_STREAM_CAPTURE], 330 runtime); 331 } 332 333 static int loopback_prepare(struct snd_pcm_substream *substream) 334 { 335 struct snd_pcm_runtime *runtime = substream->runtime; 336 struct loopback_pcm *dpcm = runtime->private_data; 337 struct loopback_cable *cable = dpcm->cable; 338 int bps, salign; 339 340 salign = (snd_pcm_format_width(runtime->format) * 341 runtime->channels) / 8; 342 bps = salign * runtime->rate; 343 if (bps <= 0 || salign <= 0) 344 return -EINVAL; 345 346 dpcm->buf_pos = 0; 347 dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size); 348 if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) { 349 /* clear capture buffer */ 350 dpcm->silent_size = dpcm->pcm_buffer_size; 351 snd_pcm_format_set_silence(runtime->format, runtime->dma_area, 352 runtime->buffer_size * runtime->channels); 353 } 354 355 dpcm->irq_pos = 0; 356 dpcm->period_update_pending = 0; 357 dpcm->pcm_bps = bps; 358 dpcm->pcm_salign = salign; 359 dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size); 360 361 mutex_lock(&dpcm->loopback->cable_lock); 362 if (!(cable->valid & ~(1 << substream->stream)) || 363 (get_setup(dpcm)->notify && 364 substream->stream == SNDRV_PCM_STREAM_PLAYBACK)) 365 params_change(substream); 366 cable->valid |= 1 << substream->stream; 367 mutex_unlock(&dpcm->loopback->cable_lock); 368 369 return 0; 370 } 371 372 static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes) 373 { 374 struct snd_pcm_runtime *runtime = dpcm->substream->runtime; 375 char *dst = runtime->dma_area; 376 unsigned int dst_off = dpcm->buf_pos; 377 378 if (dpcm->silent_size >= dpcm->pcm_buffer_size) 379 return; 380 if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size) 381 bytes = dpcm->pcm_buffer_size - dpcm->silent_size; 382 383 for (;;) { 384 unsigned int size = bytes; 385 if (dst_off + size > dpcm->pcm_buffer_size) 386 size = dpcm->pcm_buffer_size - dst_off; 387 snd_pcm_format_set_silence(runtime->format, dst + dst_off, 388 bytes_to_frames(runtime, size) * 389 runtime->channels); 390 dpcm->silent_size += size; 391 bytes -= size; 392 if (!bytes) 393 break; 394 dst_off = 0; 395 } 396 } 397 398 static void copy_play_buf(struct loopback_pcm *play, 399 struct loopback_pcm *capt, 400 unsigned int bytes) 401 { 402 struct snd_pcm_runtime *runtime = play->substream->runtime; 403 char *src = runtime->dma_area; 404 char *dst = capt->substream->runtime->dma_area; 405 unsigned int src_off = play->buf_pos; 406 unsigned int dst_off = capt->buf_pos; 407 unsigned int clear_bytes = 0; 408 409 /* check if playback is draining, trim the capture copy size 410 * when our pointer is at the end of playback ring buffer */ 411 if (runtime->status->state == SNDRV_PCM_STATE_DRAINING && 412 snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) { 413 snd_pcm_uframes_t appl_ptr, appl_ptr1, diff; 414 appl_ptr = appl_ptr1 = runtime->control->appl_ptr; 415 appl_ptr1 -= appl_ptr1 % runtime->buffer_size; 416 appl_ptr1 += play->buf_pos / play->pcm_salign; 417 if (appl_ptr < appl_ptr1) 418 appl_ptr1 -= runtime->buffer_size; 419 diff = (appl_ptr - appl_ptr1) * play->pcm_salign; 420 if (diff < bytes) { 421 clear_bytes = bytes - diff; 422 bytes = diff; 423 } 424 } 425 426 for (;;) { 427 unsigned int size = bytes; 428 if (src_off + size > play->pcm_buffer_size) 429 size = play->pcm_buffer_size - src_off; 430 if (dst_off + size > capt->pcm_buffer_size) 431 size = capt->pcm_buffer_size - dst_off; 432 memcpy(dst + dst_off, src + src_off, size); 433 capt->silent_size = 0; 434 bytes -= size; 435 if (!bytes) 436 break; 437 src_off = (src_off + size) % play->pcm_buffer_size; 438 dst_off = (dst_off + size) % capt->pcm_buffer_size; 439 } 440 441 if (clear_bytes > 0) { 442 clear_capture_buf(capt, clear_bytes); 443 capt->silent_size = 0; 444 } 445 } 446 447 #define BYTEPOS_UPDATE_POSONLY 0 448 #define BYTEPOS_UPDATE_CLEAR 1 449 #define BYTEPOS_UPDATE_COPY 2 450 451 static void loopback_bytepos_update(struct loopback_pcm *dpcm, 452 unsigned int delta, 453 unsigned int cmd) 454 { 455 unsigned int count; 456 unsigned long last_pos; 457 458 last_pos = byte_pos(dpcm, dpcm->irq_pos); 459 dpcm->irq_pos += delta * dpcm->pcm_bps; 460 count = byte_pos(dpcm, dpcm->irq_pos) - last_pos; 461 if (!count) 462 return; 463 if (cmd == BYTEPOS_UPDATE_CLEAR) 464 clear_capture_buf(dpcm, count); 465 else if (cmd == BYTEPOS_UPDATE_COPY) 466 copy_play_buf(dpcm->cable->streams[SNDRV_PCM_STREAM_PLAYBACK], 467 dpcm->cable->streams[SNDRV_PCM_STREAM_CAPTURE], 468 count); 469 dpcm->buf_pos += count; 470 dpcm->buf_pos %= dpcm->pcm_buffer_size; 471 if (dpcm->irq_pos >= dpcm->period_size_frac) { 472 dpcm->irq_pos %= dpcm->period_size_frac; 473 dpcm->period_update_pending = 1; 474 } 475 } 476 477 static unsigned int loopback_pos_update(struct loopback_cable *cable) 478 { 479 struct loopback_pcm *dpcm_play = 480 cable->streams[SNDRV_PCM_STREAM_PLAYBACK]; 481 struct loopback_pcm *dpcm_capt = 482 cable->streams[SNDRV_PCM_STREAM_CAPTURE]; 483 unsigned long delta_play = 0, delta_capt = 0; 484 unsigned int running; 485 unsigned long flags; 486 487 spin_lock_irqsave(&cable->lock, flags); 488 running = cable->running ^ cable->pause; 489 if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) { 490 delta_play = jiffies - dpcm_play->last_jiffies; 491 dpcm_play->last_jiffies += delta_play; 492 } 493 494 if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) { 495 delta_capt = jiffies - dpcm_capt->last_jiffies; 496 dpcm_capt->last_jiffies += delta_capt; 497 } 498 499 if (delta_play == 0 && delta_capt == 0) 500 goto unlock; 501 502 if (delta_play > delta_capt) { 503 loopback_bytepos_update(dpcm_play, delta_play - delta_capt, 504 BYTEPOS_UPDATE_POSONLY); 505 delta_play = delta_capt; 506 } else if (delta_play < delta_capt) { 507 loopback_bytepos_update(dpcm_capt, delta_capt - delta_play, 508 BYTEPOS_UPDATE_CLEAR); 509 delta_capt = delta_play; 510 } 511 512 if (delta_play == 0 && delta_capt == 0) 513 goto unlock; 514 515 /* note delta_capt == delta_play at this moment */ 516 loopback_bytepos_update(dpcm_capt, delta_capt, BYTEPOS_UPDATE_COPY); 517 loopback_bytepos_update(dpcm_play, delta_play, BYTEPOS_UPDATE_POSONLY); 518 unlock: 519 spin_unlock_irqrestore(&cable->lock, flags); 520 return running; 521 } 522 523 static void loopback_timer_function(unsigned long data) 524 { 525 struct loopback_pcm *dpcm = (struct loopback_pcm *)data; 526 unsigned int running; 527 528 running = loopback_pos_update(dpcm->cable); 529 if (running & (1 << dpcm->substream->stream)) { 530 loopback_timer_start(dpcm); 531 if (dpcm->period_update_pending) { 532 dpcm->period_update_pending = 0; 533 snd_pcm_period_elapsed(dpcm->substream); 534 } 535 } 536 } 537 538 static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream) 539 { 540 struct snd_pcm_runtime *runtime = substream->runtime; 541 struct loopback_pcm *dpcm = runtime->private_data; 542 543 loopback_pos_update(dpcm->cable); 544 return bytes_to_frames(runtime, dpcm->buf_pos); 545 } 546 547 static struct snd_pcm_hardware loopback_pcm_hardware = 548 { 549 .info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP | 550 SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE), 551 .formats = (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE | 552 SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE | 553 SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE), 554 .rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000, 555 .rate_min = 8000, 556 .rate_max = 192000, 557 .channels_min = 1, 558 .channels_max = 32, 559 .buffer_bytes_max = 2 * 1024 * 1024, 560 .period_bytes_min = 64, 561 /* note check overflow in frac_pos() using pcm_rate_shift before 562 changing period_bytes_max value */ 563 .period_bytes_max = 1024 * 1024, 564 .periods_min = 1, 565 .periods_max = 1024, 566 .fifo_size = 0, 567 }; 568 569 static void loopback_runtime_free(struct snd_pcm_runtime *runtime) 570 { 571 struct loopback_pcm *dpcm = runtime->private_data; 572 kfree(dpcm); 573 } 574 575 static int loopback_hw_params(struct snd_pcm_substream *substream, 576 struct snd_pcm_hw_params *params) 577 { 578 return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params)); 579 } 580 581 static int loopback_hw_free(struct snd_pcm_substream *substream) 582 { 583 struct snd_pcm_runtime *runtime = substream->runtime; 584 struct loopback_pcm *dpcm = runtime->private_data; 585 struct loopback_cable *cable = dpcm->cable; 586 587 mutex_lock(&dpcm->loopback->cable_lock); 588 cable->valid &= ~(1 << substream->stream); 589 mutex_unlock(&dpcm->loopback->cable_lock); 590 return snd_pcm_lib_free_pages(substream); 591 } 592 593 static unsigned int get_cable_index(struct snd_pcm_substream *substream) 594 { 595 if (!substream->pcm->device) 596 return substream->stream; 597 else 598 return !substream->stream; 599 } 600 601 static int rule_format(struct snd_pcm_hw_params *params, 602 struct snd_pcm_hw_rule *rule) 603 { 604 605 struct snd_pcm_hardware *hw = rule->private; 606 struct snd_mask *maskp = hw_param_mask(params, rule->var); 607 608 maskp->bits[0] &= (u_int32_t)hw->formats; 609 maskp->bits[1] &= (u_int32_t)(hw->formats >> 32); 610 memset(maskp->bits + 2, 0, (SNDRV_MASK_MAX-64) / 8); /* clear rest */ 611 if (! maskp->bits[0] && ! maskp->bits[1]) 612 return -EINVAL; 613 return 0; 614 } 615 616 static int rule_rate(struct snd_pcm_hw_params *params, 617 struct snd_pcm_hw_rule *rule) 618 { 619 struct snd_pcm_hardware *hw = rule->private; 620 struct snd_interval t; 621 622 t.min = hw->rate_min; 623 t.max = hw->rate_max; 624 t.openmin = t.openmax = 0; 625 t.integer = 0; 626 return snd_interval_refine(hw_param_interval(params, rule->var), &t); 627 } 628 629 static int rule_channels(struct snd_pcm_hw_params *params, 630 struct snd_pcm_hw_rule *rule) 631 { 632 struct snd_pcm_hardware *hw = rule->private; 633 struct snd_interval t; 634 635 t.min = hw->channels_min; 636 t.max = hw->channels_max; 637 t.openmin = t.openmax = 0; 638 t.integer = 0; 639 return snd_interval_refine(hw_param_interval(params, rule->var), &t); 640 } 641 642 static int loopback_open(struct snd_pcm_substream *substream) 643 { 644 struct snd_pcm_runtime *runtime = substream->runtime; 645 struct loopback *loopback = substream->private_data; 646 struct loopback_pcm *dpcm; 647 struct loopback_cable *cable; 648 int err = 0; 649 int dev = get_cable_index(substream); 650 651 mutex_lock(&loopback->cable_lock); 652 dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL); 653 if (!dpcm) { 654 err = -ENOMEM; 655 goto unlock; 656 } 657 dpcm->loopback = loopback; 658 dpcm->substream = substream; 659 setup_timer(&dpcm->timer, loopback_timer_function, 660 (unsigned long)dpcm); 661 662 cable = loopback->cables[substream->number][dev]; 663 if (!cable) { 664 cable = kzalloc(sizeof(*cable), GFP_KERNEL); 665 if (!cable) { 666 kfree(dpcm); 667 err = -ENOMEM; 668 goto unlock; 669 } 670 spin_lock_init(&cable->lock); 671 cable->hw = loopback_pcm_hardware; 672 loopback->cables[substream->number][dev] = cable; 673 } 674 dpcm->cable = cable; 675 cable->streams[substream->stream] = dpcm; 676 677 snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS); 678 679 /* use dynamic rules based on actual runtime->hw values */ 680 /* note that the default rules created in the PCM midlevel code */ 681 /* are cached -> they do not reflect the actual state */ 682 err = snd_pcm_hw_rule_add(runtime, 0, 683 SNDRV_PCM_HW_PARAM_FORMAT, 684 rule_format, &runtime->hw, 685 SNDRV_PCM_HW_PARAM_FORMAT, -1); 686 if (err < 0) 687 goto unlock; 688 err = snd_pcm_hw_rule_add(runtime, 0, 689 SNDRV_PCM_HW_PARAM_RATE, 690 rule_rate, &runtime->hw, 691 SNDRV_PCM_HW_PARAM_RATE, -1); 692 if (err < 0) 693 goto unlock; 694 err = snd_pcm_hw_rule_add(runtime, 0, 695 SNDRV_PCM_HW_PARAM_CHANNELS, 696 rule_channels, &runtime->hw, 697 SNDRV_PCM_HW_PARAM_CHANNELS, -1); 698 if (err < 0) 699 goto unlock; 700 701 runtime->private_data = dpcm; 702 runtime->private_free = loopback_runtime_free; 703 if (get_notify(dpcm)) 704 runtime->hw = loopback_pcm_hardware; 705 else 706 runtime->hw = cable->hw; 707 unlock: 708 mutex_unlock(&loopback->cable_lock); 709 return err; 710 } 711 712 static int loopback_close(struct snd_pcm_substream *substream) 713 { 714 struct loopback *loopback = substream->private_data; 715 struct loopback_pcm *dpcm = substream->runtime->private_data; 716 struct loopback_cable *cable; 717 int dev = get_cable_index(substream); 718 719 loopback_timer_stop(dpcm); 720 mutex_lock(&loopback->cable_lock); 721 cable = loopback->cables[substream->number][dev]; 722 if (cable->streams[!substream->stream]) { 723 /* other stream is still alive */ 724 cable->streams[substream->stream] = NULL; 725 } else { 726 /* free the cable */ 727 loopback->cables[substream->number][dev] = NULL; 728 kfree(cable); 729 } 730 mutex_unlock(&loopback->cable_lock); 731 return 0; 732 } 733 734 static struct snd_pcm_ops loopback_playback_ops = { 735 .open = loopback_open, 736 .close = loopback_close, 737 .ioctl = snd_pcm_lib_ioctl, 738 .hw_params = loopback_hw_params, 739 .hw_free = loopback_hw_free, 740 .prepare = loopback_prepare, 741 .trigger = loopback_trigger, 742 .pointer = loopback_pointer, 743 }; 744 745 static struct snd_pcm_ops loopback_capture_ops = { 746 .open = loopback_open, 747 .close = loopback_close, 748 .ioctl = snd_pcm_lib_ioctl, 749 .hw_params = loopback_hw_params, 750 .hw_free = loopback_hw_free, 751 .prepare = loopback_prepare, 752 .trigger = loopback_trigger, 753 .pointer = loopback_pointer, 754 }; 755 756 static int __devinit loopback_pcm_new(struct loopback *loopback, 757 int device, int substreams) 758 { 759 struct snd_pcm *pcm; 760 int err; 761 762 err = snd_pcm_new(loopback->card, "Loopback PCM", device, 763 substreams, substreams, &pcm); 764 if (err < 0) 765 return err; 766 snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_playback_ops); 767 snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_capture_ops); 768 769 pcm->private_data = loopback; 770 pcm->info_flags = 0; 771 strcpy(pcm->name, "Loopback PCM"); 772 773 loopback->pcm[device] = pcm; 774 775 snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS, 776 snd_dma_continuous_data(GFP_KERNEL), 777 0, 2 * 1024 * 1024); 778 return 0; 779 } 780 781 static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol, 782 struct snd_ctl_elem_info *uinfo) 783 { 784 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER; 785 uinfo->count = 1; 786 uinfo->value.integer.min = 80000; 787 uinfo->value.integer.max = 120000; 788 uinfo->value.integer.step = 1; 789 return 0; 790 } 791 792 static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol, 793 struct snd_ctl_elem_value *ucontrol) 794 { 795 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 796 797 ucontrol->value.integer.value[0] = 798 loopback->setup[kcontrol->id.subdevice] 799 [kcontrol->id.device].rate_shift; 800 return 0; 801 } 802 803 static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol, 804 struct snd_ctl_elem_value *ucontrol) 805 { 806 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 807 unsigned int val; 808 int change = 0; 809 810 val = ucontrol->value.integer.value[0]; 811 if (val < 80000) 812 val = 80000; 813 if (val > 120000) 814 val = 120000; 815 mutex_lock(&loopback->cable_lock); 816 if (val != loopback->setup[kcontrol->id.subdevice] 817 [kcontrol->id.device].rate_shift) { 818 loopback->setup[kcontrol->id.subdevice] 819 [kcontrol->id.device].rate_shift = val; 820 change = 1; 821 } 822 mutex_unlock(&loopback->cable_lock); 823 return change; 824 } 825 826 static int loopback_notify_get(struct snd_kcontrol *kcontrol, 827 struct snd_ctl_elem_value *ucontrol) 828 { 829 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 830 831 ucontrol->value.integer.value[0] = 832 loopback->setup[kcontrol->id.subdevice] 833 [kcontrol->id.device].notify; 834 return 0; 835 } 836 837 static int loopback_notify_put(struct snd_kcontrol *kcontrol, 838 struct snd_ctl_elem_value *ucontrol) 839 { 840 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 841 unsigned int val; 842 int change = 0; 843 844 val = ucontrol->value.integer.value[0] ? 1 : 0; 845 if (val != loopback->setup[kcontrol->id.subdevice] 846 [kcontrol->id.device].notify) { 847 loopback->setup[kcontrol->id.subdevice] 848 [kcontrol->id.device].notify = val; 849 change = 1; 850 } 851 return change; 852 } 853 854 static int loopback_active_get(struct snd_kcontrol *kcontrol, 855 struct snd_ctl_elem_value *ucontrol) 856 { 857 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 858 struct loopback_cable *cable = loopback->cables 859 [kcontrol->id.subdevice][kcontrol->id.device ^ 1]; 860 unsigned int val = 0; 861 862 if (cable != NULL) 863 val = (cable->running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 864 1 : 0; 865 ucontrol->value.integer.value[0] = val; 866 return 0; 867 } 868 869 static int loopback_format_info(struct snd_kcontrol *kcontrol, 870 struct snd_ctl_elem_info *uinfo) 871 { 872 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER; 873 uinfo->count = 1; 874 uinfo->value.integer.min = 0; 875 uinfo->value.integer.max = SNDRV_PCM_FORMAT_LAST; 876 uinfo->value.integer.step = 1; 877 return 0; 878 } 879 880 static int loopback_format_get(struct snd_kcontrol *kcontrol, 881 struct snd_ctl_elem_value *ucontrol) 882 { 883 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 884 885 ucontrol->value.integer.value[0] = 886 loopback->setup[kcontrol->id.subdevice] 887 [kcontrol->id.device].format; 888 return 0; 889 } 890 891 static int loopback_rate_info(struct snd_kcontrol *kcontrol, 892 struct snd_ctl_elem_info *uinfo) 893 { 894 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER; 895 uinfo->count = 1; 896 uinfo->value.integer.min = 0; 897 uinfo->value.integer.max = 192000; 898 uinfo->value.integer.step = 1; 899 return 0; 900 } 901 902 static int loopback_rate_get(struct snd_kcontrol *kcontrol, 903 struct snd_ctl_elem_value *ucontrol) 904 { 905 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 906 907 ucontrol->value.integer.value[0] = 908 loopback->setup[kcontrol->id.subdevice] 909 [kcontrol->id.device].rate; 910 return 0; 911 } 912 913 static int loopback_channels_info(struct snd_kcontrol *kcontrol, 914 struct snd_ctl_elem_info *uinfo) 915 { 916 uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER; 917 uinfo->count = 1; 918 uinfo->value.integer.min = 1; 919 uinfo->value.integer.max = 1024; 920 uinfo->value.integer.step = 1; 921 return 0; 922 } 923 924 static int loopback_channels_get(struct snd_kcontrol *kcontrol, 925 struct snd_ctl_elem_value *ucontrol) 926 { 927 struct loopback *loopback = snd_kcontrol_chip(kcontrol); 928 929 ucontrol->value.integer.value[0] = 930 loopback->setup[kcontrol->id.subdevice] 931 [kcontrol->id.device].channels; 932 return 0; 933 } 934 935 static struct snd_kcontrol_new loopback_controls[] __devinitdata = { 936 { 937 .iface = SNDRV_CTL_ELEM_IFACE_PCM, 938 .name = "PCM Rate Shift 100000", 939 .info = loopback_rate_shift_info, 940 .get = loopback_rate_shift_get, 941 .put = loopback_rate_shift_put, 942 }, 943 { 944 .iface = SNDRV_CTL_ELEM_IFACE_PCM, 945 .name = "PCM Notify", 946 .info = snd_ctl_boolean_mono_info, 947 .get = loopback_notify_get, 948 .put = loopback_notify_put, 949 }, 950 #define ACTIVE_IDX 2 951 { 952 .access = SNDRV_CTL_ELEM_ACCESS_READ, 953 .iface = SNDRV_CTL_ELEM_IFACE_PCM, 954 .name = "PCM Slave Active", 955 .info = snd_ctl_boolean_mono_info, 956 .get = loopback_active_get, 957 }, 958 #define FORMAT_IDX 3 959 { 960 .access = SNDRV_CTL_ELEM_ACCESS_READ, 961 .iface = SNDRV_CTL_ELEM_IFACE_PCM, 962 .name = "PCM Slave Format", 963 .info = loopback_format_info, 964 .get = loopback_format_get 965 }, 966 #define RATE_IDX 4 967 { 968 .access = SNDRV_CTL_ELEM_ACCESS_READ, 969 .iface = SNDRV_CTL_ELEM_IFACE_PCM, 970 .name = "PCM Slave Rate", 971 .info = loopback_rate_info, 972 .get = loopback_rate_get 973 }, 974 #define CHANNELS_IDX 5 975 { 976 .access = SNDRV_CTL_ELEM_ACCESS_READ, 977 .iface = SNDRV_CTL_ELEM_IFACE_PCM, 978 .name = "PCM Slave Channels", 979 .info = loopback_channels_info, 980 .get = loopback_channels_get 981 } 982 }; 983 984 static int __devinit loopback_mixer_new(struct loopback *loopback, int notify) 985 { 986 struct snd_card *card = loopback->card; 987 struct snd_pcm *pcm; 988 struct snd_kcontrol *kctl; 989 struct loopback_setup *setup; 990 int err, dev, substr, substr_count, idx; 991 992 strcpy(card->mixername, "Loopback Mixer"); 993 for (dev = 0; dev < 2; dev++) { 994 pcm = loopback->pcm[dev]; 995 substr_count = 996 pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count; 997 for (substr = 0; substr < substr_count; substr++) { 998 setup = &loopback->setup[substr][dev]; 999 setup->notify = notify; 1000 setup->rate_shift = NO_PITCH; 1001 setup->format = SNDRV_PCM_FORMAT_S16_LE; 1002 setup->rate = 48000; 1003 setup->channels = 2; 1004 for (idx = 0; idx < ARRAY_SIZE(loopback_controls); 1005 idx++) { 1006 kctl = snd_ctl_new1(&loopback_controls[idx], 1007 loopback); 1008 if (!kctl) 1009 return -ENOMEM; 1010 kctl->id.device = dev; 1011 kctl->id.subdevice = substr; 1012 switch (idx) { 1013 case ACTIVE_IDX: 1014 setup->active_id = kctl->id; 1015 break; 1016 case FORMAT_IDX: 1017 setup->format_id = kctl->id; 1018 break; 1019 case RATE_IDX: 1020 setup->rate_id = kctl->id; 1021 break; 1022 case CHANNELS_IDX: 1023 setup->channels_id = kctl->id; 1024 break; 1025 default: 1026 break; 1027 } 1028 err = snd_ctl_add(card, kctl); 1029 if (err < 0) 1030 return err; 1031 } 1032 } 1033 } 1034 return 0; 1035 } 1036 1037 #ifdef CONFIG_PROC_FS 1038 1039 static void print_dpcm_info(struct snd_info_buffer *buffer, 1040 struct loopback_pcm *dpcm, 1041 const char *id) 1042 { 1043 snd_iprintf(buffer, " %s\n", id); 1044 if (dpcm == NULL) { 1045 snd_iprintf(buffer, " inactive\n"); 1046 return; 1047 } 1048 snd_iprintf(buffer, " buffer_size:\t%u\n", dpcm->pcm_buffer_size); 1049 snd_iprintf(buffer, " buffer_pos:\t\t%u\n", dpcm->buf_pos); 1050 snd_iprintf(buffer, " silent_size:\t%u\n", dpcm->silent_size); 1051 snd_iprintf(buffer, " period_size:\t%u\n", dpcm->pcm_period_size); 1052 snd_iprintf(buffer, " bytes_per_sec:\t%u\n", dpcm->pcm_bps); 1053 snd_iprintf(buffer, " sample_align:\t%u\n", dpcm->pcm_salign); 1054 snd_iprintf(buffer, " rate_shift:\t\t%u\n", dpcm->pcm_rate_shift); 1055 snd_iprintf(buffer, " update_pending:\t%u\n", 1056 dpcm->period_update_pending); 1057 snd_iprintf(buffer, " irq_pos:\t\t%u\n", dpcm->irq_pos); 1058 snd_iprintf(buffer, " period_frac:\t%u\n", dpcm->period_size_frac); 1059 snd_iprintf(buffer, " last_jiffies:\t%lu (%lu)\n", 1060 dpcm->last_jiffies, jiffies); 1061 snd_iprintf(buffer, " timer_expires:\t%lu\n", dpcm->timer.expires); 1062 } 1063 1064 static void print_substream_info(struct snd_info_buffer *buffer, 1065 struct loopback *loopback, 1066 int sub, 1067 int num) 1068 { 1069 struct loopback_cable *cable = loopback->cables[sub][num]; 1070 1071 snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub); 1072 if (cable == NULL) { 1073 snd_iprintf(buffer, " inactive\n"); 1074 return; 1075 } 1076 snd_iprintf(buffer, " valid: %u\n", cable->valid); 1077 snd_iprintf(buffer, " running: %u\n", cable->running); 1078 snd_iprintf(buffer, " pause: %u\n", cable->pause); 1079 print_dpcm_info(buffer, cable->streams[0], "Playback"); 1080 print_dpcm_info(buffer, cable->streams[1], "Capture"); 1081 } 1082 1083 static void print_cable_info(struct snd_info_entry *entry, 1084 struct snd_info_buffer *buffer) 1085 { 1086 struct loopback *loopback = entry->private_data; 1087 int sub, num; 1088 1089 mutex_lock(&loopback->cable_lock); 1090 num = entry->name[strlen(entry->name)-1]; 1091 num = num == '0' ? 0 : 1; 1092 for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++) 1093 print_substream_info(buffer, loopback, sub, num); 1094 mutex_unlock(&loopback->cable_lock); 1095 } 1096 1097 static int __devinit loopback_proc_new(struct loopback *loopback, int cidx) 1098 { 1099 char name[32]; 1100 struct snd_info_entry *entry; 1101 int err; 1102 1103 snprintf(name, sizeof(name), "cable#%d", cidx); 1104 err = snd_card_proc_new(loopback->card, name, &entry); 1105 if (err < 0) 1106 return err; 1107 1108 snd_info_set_text_ops(entry, loopback, print_cable_info); 1109 return 0; 1110 } 1111 1112 #else /* !CONFIG_PROC_FS */ 1113 1114 #define loopback_proc_new(loopback, cidx) do { } while (0) 1115 1116 #endif 1117 1118 static int __devinit loopback_probe(struct platform_device *devptr) 1119 { 1120 struct snd_card *card; 1121 struct loopback *loopback; 1122 int dev = devptr->id; 1123 int err; 1124 1125 err = snd_card_create(index[dev], id[dev], THIS_MODULE, 1126 sizeof(struct loopback), &card); 1127 if (err < 0) 1128 return err; 1129 loopback = card->private_data; 1130 1131 if (pcm_substreams[dev] < 1) 1132 pcm_substreams[dev] = 1; 1133 if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS) 1134 pcm_substreams[dev] = MAX_PCM_SUBSTREAMS; 1135 1136 loopback->card = card; 1137 mutex_init(&loopback->cable_lock); 1138 1139 err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]); 1140 if (err < 0) 1141 goto __nodev; 1142 err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]); 1143 if (err < 0) 1144 goto __nodev; 1145 err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0); 1146 if (err < 0) 1147 goto __nodev; 1148 loopback_proc_new(loopback, 0); 1149 loopback_proc_new(loopback, 1); 1150 strcpy(card->driver, "Loopback"); 1151 strcpy(card->shortname, "Loopback"); 1152 sprintf(card->longname, "Loopback %i", dev + 1); 1153 err = snd_card_register(card); 1154 if (!err) { 1155 platform_set_drvdata(devptr, card); 1156 return 0; 1157 } 1158 __nodev: 1159 snd_card_free(card); 1160 return err; 1161 } 1162 1163 static int __devexit loopback_remove(struct platform_device *devptr) 1164 { 1165 snd_card_free(platform_get_drvdata(devptr)); 1166 platform_set_drvdata(devptr, NULL); 1167 return 0; 1168 } 1169 1170 #ifdef CONFIG_PM 1171 static int loopback_suspend(struct platform_device *pdev, 1172 pm_message_t state) 1173 { 1174 struct snd_card *card = platform_get_drvdata(pdev); 1175 struct loopback *loopback = card->private_data; 1176 1177 snd_power_change_state(card, SNDRV_CTL_POWER_D3hot); 1178 1179 snd_pcm_suspend_all(loopback->pcm[0]); 1180 snd_pcm_suspend_all(loopback->pcm[1]); 1181 return 0; 1182 } 1183 1184 static int loopback_resume(struct platform_device *pdev) 1185 { 1186 struct snd_card *card = platform_get_drvdata(pdev); 1187 1188 snd_power_change_state(card, SNDRV_CTL_POWER_D0); 1189 return 0; 1190 } 1191 #endif 1192 1193 #define SND_LOOPBACK_DRIVER "snd_aloop" 1194 1195 static struct platform_driver loopback_driver = { 1196 .probe = loopback_probe, 1197 .remove = __devexit_p(loopback_remove), 1198 #ifdef CONFIG_PM 1199 .suspend = loopback_suspend, 1200 .resume = loopback_resume, 1201 #endif 1202 .driver = { 1203 .name = SND_LOOPBACK_DRIVER 1204 }, 1205 }; 1206 1207 static void loopback_unregister_all(void) 1208 { 1209 int i; 1210 1211 for (i = 0; i < ARRAY_SIZE(devices); ++i) 1212 platform_device_unregister(devices[i]); 1213 platform_driver_unregister(&loopback_driver); 1214 } 1215 1216 static int __init alsa_card_loopback_init(void) 1217 { 1218 int i, err, cards; 1219 1220 err = platform_driver_register(&loopback_driver); 1221 if (err < 0) 1222 return err; 1223 1224 1225 cards = 0; 1226 for (i = 0; i < SNDRV_CARDS; i++) { 1227 struct platform_device *device; 1228 if (!enable[i]) 1229 continue; 1230 device = platform_device_register_simple(SND_LOOPBACK_DRIVER, 1231 i, NULL, 0); 1232 if (IS_ERR(device)) 1233 continue; 1234 if (!platform_get_drvdata(device)) { 1235 platform_device_unregister(device); 1236 continue; 1237 } 1238 devices[i] = device; 1239 cards++; 1240 } 1241 if (!cards) { 1242 #ifdef MODULE 1243 printk(KERN_ERR "aloop: No loopback enabled\n"); 1244 #endif 1245 loopback_unregister_all(); 1246 return -ENODEV; 1247 } 1248 return 0; 1249 } 1250 1251 static void __exit alsa_card_loopback_exit(void) 1252 { 1253 loopback_unregister_all(); 1254 } 1255 1256 module_init(alsa_card_loopback_init) 1257 module_exit(alsa_card_loopback_exit) 1258